Lubricating compositions



3,048,542 Patented Aug. 7, T1962 free 3,048,542 LUBRICATENG CUR {POSITIONS} Raymond B. Tierney, Wappingers Falls, and Robert H. Krug, Cornwall, N.Y., assignors to Texaco Inc, a cor-= poration of Delaware No Drawing. Filed Jan. 30, 1959, Ser. No. 790,037 13 Claims. (Cl. 252-475) This invention relates to a lubricating composition which is particularly designed for lubrication of turbine engines which operate over a wide temperature range and under severe operating conditions. More particularly, this invention concerns a synthetic lubricating composition having very superior non-corrosive, extreme pressure properties. This application is a continuationin-part of copending application Serial No. 593,381, filed June 25, 1956, now abandoned.

In many instances mineral oil base lubricants are not satisfactory for the lubrication of modern turbines which are operated under severe conditions. Turbine engines used to power jet aircraft in particular require lubricants which will withstand the stress to which they are submitted. Synthetic base lubricants of the ester-base type have been found to be extremely useful in meeting the particular requirements for lubrication of jet turbine engines. However, even these superior base components need to be tailored to meet certain engine requirements set forth by the military and commercial aircraft engine manufacturers. It is particularly difficult to achieve a synthetic oil composition having properties enabling it to withstand extreme stress without becoming corrosive due to excessive oxidation of the components.

The lubricant composition of this invention broadly comprises a polyester-type base fluid and a fatty material consisting essentially of a compound selected from the group consisting of dimers and trimers of ethylenic fatty acids, and mixtures thereof, said fatty acids having from 12 to 22 carbon atoms and said material being present in an amount sufficient to lend extreme pressure properties to the composition. The effective amounts of the El. additives in the base oil range from 0.01 to 1 percent by weight, however, the preferred amounts range from 0.05 to 0.15 weight percent. An increase in additive amounts over the prescribed broad range does not increase the load-carrying ability of the lubricant composition appreciably and tends to increase lead corrosion tendencies thereof. The preferred dimer and trimer acids are prepared using linoleic acid as a polyethylenic component.

Although the dimer and trimer acid material contain none of the elements usually associated with ER activity, such as chlorine, phosphorus, or sulfur, they have been found to give significant increases in the load carrying levels of synthetic lubricants without imparting corrosive tendencies to the composition.

Dimerized fatty acids are well known in the art as anti-corrosive additives in both lubricant and non-lubricant mineral oils and as intermediates in the preparation of other mineral oil additives. Their preparation and physical properties are set forth in varying degrees in such U.S. patents as 2,482,761 to Goebel, 2,631,979 to McDermott, and 2,632,695 to Landis et a1. It has been shown that material consisting primarily of the dimer acid can be prepared by subjecting unsaturated fatty acids to moderate steam pressures of from 80 to 300 pounds per square inch, at temperatures of from 260 to 360 C. for a period of from about 3 to 8 hours.

Another method for preparing the dimer acids broadly comprises heating a short chain aliphatic alcohol ester of an ethylenic fatty acid at about 300 C. for several hours in an inert atmosphere. The resulting dimerized ester is then separated by distillation and hydrolyzed with hydrochloric acid or its equivalent. Fatty oils have also been heat polymerized and thereafter hydrolyzed to produce dimer acids. The first mentioned method is preferred, however, owing to the fact that a larger percentage of dimer acids are produced from the starting materials by the utilization of that method of production.

The trimer acid material is quite easily obtained. It can be separated as it forms along with monomers and higher polymer acids during the preparation of dimer acids by the methods just described. In the case of the trimer acids, however, conventional methods for preparing polymer acids are preferred over the method of Goebel 2,482,761, wherein unsaturated acids are subjected to moderate steam pressure, at moderate temperature for a few hours, since these other methods produce higher percentages of trimer acid material.

The mixture of dimer and trimer acids formed in these processes are at times, for commercial reasons, separated from monomeric and higher polymeric material present as well as from each other. However, the dimer and trimer acids of the invention can be used as BF. additives for the synthetic base fluids described either separately, mixed or with minor non-degrading amounts of monomer and higher polymer acids.

The dimer and trimer acids of the present invention,

\ although preferably conjugation products of two and three of the same molecules which are dior polyethylenic, are also products of the combination of monoetliylenic compounds and polyethylenic compounds. For instance, linoleic acid and oleic acid dimerized to become the dimer of linoleic and oleic acids. It is, however, necessary to have at least one polyethylenic compound present to form the dimer and trimer.

The fatty acids useful in accordance with this invention include ethylenic monocarboxylic acids having from 12 to 22 carbon atoms examples of which are as follows: 4-dodecenoic, 5,9-dimethyl-2,8-decadienoic, myristoleic, palmitoleic, oleic, linoleic (9,1l-octadecadienoic, 10,12- octadecadienoic and 11,13-octadecadienoic) linolenic, erucic and 13,15-docosadienoic. The preferred acid is linoleic acid on the basis of availability and cost. Good source materials from which these fatty acids can be obtained by hydrolysis are vegetable oils, such as soybean oil, linseed oil, cotton seed oil, corn oil, castor oil, mustard seed oil, and peanut oil.

Examples of the percentage composition of some fatty materials consisting essentially of a dimer acid, trimer acid or mixtures thereof which are useful in accordance with the invention are as follows:

Wt. percent (1) Dimer acid 78 Trimer and higher polymer acids 22 (2) Dimer acid 72 Trimer and higher polymer acids 20 Monomer acid 8 (3) Dimer acid Trimer and higher polymer acids 12 Monomer acid 3 (4) Dimer acid 92 Trimer and higher polymer acids 6 Monomer acids 1.5 Fatty residue material 0.5

(5) Dimer acid 99.5 Fatty residue material 0.5

(6) Trimer acid 53 Dimer acid 35 Monomer acid 6 Higher polymer acid and fatty residue 6 Wt. percent (7) Trimer acid 85 Dimer acid 6 Higher polymer acid Monomer acid 4 (8) Trimer acid 65 Dimer acid 35 (9) Trimer acid 98 Fatty residue 2 The most commonly used ester base lubricant is an aliphatic diester of an organic dicarboxylic acid. The dicarboxylic acid component is usually an aliphatic dicarboxylic acid containing 6 to 12 carbon atoms but glutaric acid esters and succinic acid esters may also be used. From the standpoint of cost and availability, the preferred dibasic acids are adipic acid, sebacic acid and azelaic acid. The aliphatic alcohols used to form the diesters usually contain at least 4 carbon atoms and may contain or more carbon atoms. C to C alcohols are most commonly used. Ether alcohols, such as Cellosolve and Carbitol may also be used in the formation of the aliphatic diesters of organic dicarboxylic acids used as the lubricating base in the compositions of this invention.

Specific examples of the dialkyl esters of aliphatic dicarboxylic acids, which are the preferred base fluids for us in the lubricant composition of the invention, are as follows di-isooctyl azelate, di-Z-ethylhexyl sebacate, di-2- ethyhexyl azelate, di-2-ethylhexyl adipate, dilauryl azelate, di-sec-amyl sebacate, di-Z-ethylhexyl alkenylsuccinate, di-Z-ethoxyethyl sebacate, di-2-(2'-methoxyethoxy) ethyl sebacate, di-2-(2'-ethylbutoxy) ethyl sebacate, di-2- butoxyethyl azelate, di-2-(2'-butoxyethoxy) ethyl alkenylsuccinate, etc.

In adition to the aliphatic dicarboxylic acid esters described above, polyester lubricants formed by a reaction of an aliphatic dicarboxylic acid, a glycol and a monofunctional compound, which is either an aliphatic monohydroxy alcohol or an aliphatic monocarboxylic acid, in specified mol ratios are also employed as the synthetic lubricating base in the compositions of this invention; polyesters of this type are described in US. 2,628,974 to Robert T. Sanderson, issued February 17, 1953. Complex esters formed by reaction of a mixture containing specified amounts of 2-ethyl-1,3-hexanediol, sebacic acid and 2-ethylhexanol and by reaction of a mixture containing adipic acid, diethylene glycol and 2-ethylhexanoic acid illustrate this class of synthetic polyester lubricating bases.

Polyesters formed by reaction of a monooarboxylic acid and a glycol may also be used as the ester component. The acid component is usually an aliphatic acid containing at least 6 carbon atoms. The glycol component is advantageously a straight glycol such as 1,6-hexanediol, but ether glycol, such as tetraethylene glycol, may also be used.

Specific examples of the diesters of glycols are the following: di-n-decanoate of 1,4-butanediol, di-Z-ethylhexanoate of 1,6-hexaned-iol, dilaurate of 1,4-hexanediol, dioctanoate of 1,5-pentanediol, dilaurate of tetraethylene glycol, dilaurate of triethylene glycol, dioctoaite of pentaethylene glycol.

Complex esters formed by reacting trimethylol alkanes with various mol ratios of dibasic acids and monobasic acids or alcohols is another example of polyesters useful for the base fluid of the lubricants of this invention.

The sulfur analogs of the above-described esters are also used in the formulation of the lubricating compositions of this invention. Dithioesters are exemplified by di-2-ethylhexylthiosebacate, di-n-octyl thioadipate and the dilaurate of 1,5-pentanedithiol; sulfur analogs of polyesters are exemplified by the reaction product of adipic acid, thioglycol and Z-ethylhexyl mercaptan.

The finished lubricant composition of this invention normally contains other well known additives which act as is a particularly effective anti-oxidant and anti-corrosive agent. It inhibits corrosion by preventing oxidation of the components of the lubricating composition to acidic bodies which are inherently corrosive. Phenothiazine is usually present in a concentration of 0.1 to 1.5 Weight percent of the lubricant composition.

Various aromatic amines either alone or in combination are also known to have anti-oxidant properties and may at times be used in the present composition. For example, naphthylamines, diphenylamines and phenylene d-iamines in amounts up to about 2 percent by weight are very efiective.

Methacrylate polymers are well known V.I. improvers and pour point depressors. Polyester base lubricants, although they, per rse, possess excellent V1. and pour, usually require the presence of small concentrations of methacrylate polymers to meet the requirements of military specifications. These methacrylate polymers are usually copolymers of :two or more esters of methacrylic acid and usually have a molecular weight between 5 000 and 20,000. The methacrylate esters have the following general forwherein R is an aliphatic radical preferably ranging from butyl to stearyl.

Copolymers which find particular use as V.I. improvers and pour point depressants are the following: a copolymer wherein R in the above formula comprises 20% lauryl, 40% octyl and 40% cetyl; a copolymer wherein R in the above formula is 50% stearyl and 50% lauryl; a copolymer wherein R in the above formula comprises 50% lauryl and 50% octyl.

Methacrylate polymers are usually sold in the form of a concentrate comprising approximately 60 to 40% polymer in a carrier oil. For the lubricant compositions of this invention, it has been found advisable to use an ester-type carrier oil rather than the usual mineral base lubricating oil. The use of a methacrylate ester in an ester-type carrier oil has proven particularly effective in meeting the low temperature requirements of military specifications.

Methacrylate polymers can constitute 1 to 20 weight percent of the composition but ordinarily are used in a concentration between 1.5 and 10 Weight percent.

A Schiffs base reaction product of 1 mole of an aliphatic polyamine having two primary amino groups with 2 moles of an aromatic aldehyde having the general formula ACHNRN:CHA, where A represents an aromatic nucleus and R is an aliphatic radical having two nitrogen atoms attached directly to different carbon atoms of the same open chain, are also sometimes incorporated in the finished lubricant. Compounds of this type which generally constitute 0.05 to 1 weight percent of the composition act as metal deactivators as disclosed in the Downing et al. No. 2,282,513, issued May 12, 1942. A preferred compound of this class, which is commercially available, is disalicylal propylenediamine which is also known as disalicylidene-1,2-diaminopropane. This compound is sold under the trade name DMD by E. I. du Pont de Nemours and Company and as Tenamene 60 by Tennessee Eastman. Examples of other compounds of this type are the following:

Di-(2-hydroxy-3-methoxybenzal) ethylenediamine Di-(2-hydroxybenzal) ethylenediamine Di-(Z-hydroxybenzal) decamethylenediamine Di-(2-hydroxybenzal) triethylenetetramine Di-(Z-hydroxybenzal) hexarnethylenediamine Di-(Z-hydroxybenzal) 1:3 propylenediamine Dibenzal ethylenediamine Dibenzal hexamethylenediamine Dibenzal diethylenetriamine Dibenzal triethylenetetramine Disalicylal ethylenediamine Anti-wear agents have also been found extremely useful in synthetic lubricant preparations to be used under extreme stress such as in jet aircraft turbines. The antiwear agents preferred in the composition of the invention are tricresyl phosphate and that compound set forth and described in US. Patent No. 2,866,755, issued December 30, 1958. That patent discloses di(o-chlorophenyl) phenyl phosphate in an amount suflicient to impart El. and anti-wear properties to a synthetic lubricant composition. These phosphate additives are generally incorporated in the lubricant in amounts up to 5 wt. percent and preferably from 1 to 3 percent. Although anti-Wear compounds usually improve the BF. properties of the base lubricant, the dimer acids of the present invention provide up to /s more extreme pressure withstanding ability for the synthetic lubricant composition over any previously known E.P. agent.

Still other additive compounds can be advantageously incorporated in the lubricant composition. Detergents, such as the metal salts of phenates and sulphonates, are now widely used in lubes as dispersants. Particularly the basic salts, althouhg neutral salts are at times satis- 4O factory, have been found useful since they will neutralize any acidic products formed during oil oxidation. Sulfonates may be petroleum derivatives having molecular weights from about 300 to 500, such as calcium petroleum sulfonate or sodium petroleum sulfonate. Synthetic sulfonate detergents, such as the barium salt of wax-substituted benzene sulfonate are also available. The sulfonates either neutral or basic are used alone or in various sulfonate combinations in detergent additions to the lubricant ranging from less than one to as high as twenty percent. However, amounts ranging from 1 to 6 percent by weight of the sulfonates in the lube oil are preferred.

The phenates or phenolates useful as detergents are metal alkyl phenols or metal alkyl phenol-sulfides, such as calcium phenyl stearate, zinc alkyl salicylate, wherein the akyl group comprises olefin polymers having an average of from 12 to 30 carbon atoms, and the alkaline earth metal salts of wax-substituted phenol carboxylate sulfide. These detergents are also added to lube oils in an amount ranging from less than one up to twenty percent, however, from one to six percent by weight is preferred.

The testing of the dimer acids of this invention was performed using the test procedure and apparatus of the high speed gear scuff test. This test is intended for the evaluation of the scuff-limited load-carrying ability of those lubricants used in reduction and accessory drives of turbo-jet and turbo-prop engines. The method of test provides for the running of two spur gears in a Pratt and Whitney gear and lubricant tester (also termed the Ryder gear tester). The face width of the driven gear was 0.937 inch and the face width of the driving gear was 0.25 inch. The dynamometer speed of the gear tester was put up to 4600 r.p.m. and a loading pressure of 2.5

psi. applied. After running for 15 minutes, the tester was shut down and the driving gear removed and an estimate of the percentage of tooth area scuffed on each tooth of that gear was made. The gear was replaced and the above procedure continuously repeated using a higher loading pressure at each repetition until 22.5 percent of the total tooth face area on the driving gear had been scuffed, the load corresponding to this point being considered the scuff load. The loading pressures used were as follows: 3.5, 5, 7.5, 10, 12.5, 15, 17.5, 20, 25, 30, 35, 40, 45, 50, 6O p.s.i. and higher, increasing the load by 10 psi. until the load limit was reached. A tooth load conversion factor of 18.5 sq. in., which was a constant calculated from the product of the effective piston area of the test machine (4.52 sq. in.) and the cotangent of the helix angle of the helical gears (cot 13.7=4.10), was multiplied by the loading pressure at the scuff load and the product divided by the width of the driving gear (0.25 in.) to obtain the tooth load in pounds per inch.

The composition of a base lubricant, designated base fluid #1, tested by the above procedure was as follows:

Wt. percent Di-Z-ethylhexyl sebacate 79.4

Copolymer of 50% lauryl methacrylate and 50% stearyl methacrylate in a di-Z-ethylhexyl sebacate base oil (50% come.) -I 18.0 Di-(o-chlorophenyl) phenyl phosphate 2.0 Phenothiazine 0.5 Disalicylidene-1,2-diaminopropane 0.1

Acid value Saponification value Neut. equiv. 300 Color (Gardner) 9 Viscosity at 25 C. (Gardner-Holdt) Z4 Flash point, F. 530

The results of tests upon the foregoing synthetic composition using the high speed gear test procedure are given in the following Table I.

TABLE I High Speed Gear Test Tooth load, l b./ in. Base fluid #1 1 2390 Base fluid #1+0.1 wt. percent dimer acid material 3070; 2950 1 Average of several runs.

Tests on this same composition with the same procedure by an independent research organization. produced the following results:

TABLE II High Speed Gear Test Tooth load, lb./ in. Base fluld #1+0.1 wt. percent dimer acid material 3180; 3220 The results of the oxidation and corrosion test, the procedure of which is set forth in the military specification designated M'IL-L7808B, on the composition of the invention tested in Tables I and II, are given in the following Table III and compared to the military requirements prescribed in MILL7808B.

TABLE III Base Fluid #1 +0.1 Wt. percent; dimer acid material Oxid.-Corr. Test 347 F./72 hrs.

13 rug/sq. cm. Specification rier di-Z-ethylhexyl sebacate) 2.0 Di-(o-chlorophenyl) phenyl phosphate 1.4 Disalicylidene-l,Z-diaminopropane 0.2 Phenothiazine 1 0.5% by weight of the total composition was added.

The results of the tests on this base fluid #2 with and without dimer acid material are given in the following Table IV. The dimer acid material was as previously described.

TABLE IV High Speed Gear Test Tooth load, lb./in.

Base fluid #2 1 2065 Base fluid #2+0.05 wt. percent dimer acid material 3080; 2730 1 Average of several runs.

rier di-Z-ethylhexyl sebacate) 2.0 Tricresyl phosphate 2.0 Phenothiazine 0.5

The results of the tests on this base fluid #3 with and without the dimer acid material are given in the following Table V. As shown in the table, the amount of tricresyl phosphate was increased when the dimer material was added with a corresponding decrease in percentage amount of the di-isooctyl azclate. The dimer acid material used was that previously described.

TABLE V High Speed Gear Test Tooth load lb./in.

Base fluid #3 1 1740 Base fluid #3+an additional 0.5 wt. percent tricresyl phosphate and 0.05 wt. percent dimer acid material 2040 1 Average of several runs.

In order to demonstrate the usefulness of trimer acid material in increasing the load-carrying ability of a synthetic fluid, a fatty material consisting of about 85 percent trimer of linoleic acid was incorporated in the base fluid #4 which consisted of the following:

Percent by wt.

Di-isooctyl azelate 97.50 Copolymer of 50% lauryl methacrylate and 50% stearyl methacrylate in di-Z-ethylhexyl sebacate (50% come.) 2.0 Phenothiazine 0.5

The above comopsition and other similar compositions were tested in the high speed gear test, the results of which are given in the following table.

TABLE VI High Speed Gear Test Tooth load -lb./ in. Base fluid #4 1670; 2110 Base fluid #4+0.05 wt. percent lineoleic acid 1700; 1670 Base fluid #4+0.05 wt. percent oleic acid 1910; 1910 Base fluid #4+0.05 wt. percent dimer of linoleic acid 2330; 2330 Base fluid #4-|-0.05 Wt. percent trimer of linoleic acid 2140; 2500 The significant increases in load carrying ability which is given to synthetic lubricating oils by relatively small amounts of the non-corrosive, extreme pressure additive of this invention is amply demonstrated by the preceding tables.

Obviously, many modifications and variations of the invention as hereinabove set forth may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be made as are indicated in the appended claims.

We claim:

'1. A synthetic lubricant composition comprising a major portion of an aliphatic carboxylic acid ester having lubricating properties, selected from the group consisting of diesters and polyesters, and a minor amount suflicient to improve the extreme pressure property of the composition of a fatty material consisting essentially of a compound selected from the group consisting of dimers and trimers of linoleic acid and mixtures thereof.

2. A synthetic lubricant composition comprising a major portion of an aliphatic carboxylic acid ester having lubricating properties, selected from the group consisting of diesters and polyesters, and from 0.01 to 1 percent by weight of a fatty material consisting essentially of a compound selected from the group consisting of dimers and trimers of linoleic acid and mixtures thereof.

3. A synthetic lubricant composition as described in claim 2 wherein the ester consists of a dialkyl ester of an aliphatic dicarboxylic acid having an alkyl portion ranging from 6 to 18 carbon atoms and an aliphatic acid portion ranging from 6 to 12 carbon atoms.

4. A synthetic lubricant composition comprising a major portion of a dialkyl ester of an aliphatic dicarboxylic acid having an alkyl portion ranging from 6 to 18 carbon atoms and an aliphatic acid portion ranging from 6 to 12 carbon atoms, from 0.01 to 1 percent by weight of a fatty material consisting essentially of a compound selected from the group consisting of dimers and trimers of linoleic acid and mixtures thereof, a viscosity index improving amount of a methacrylate polymer, an oxidation inhibiting amount of phenothiazine, and di(o-ch1oropheny1)phenyl phosphate in an amount suflicient to improve the anti-wear properties of the lubricant.

5. A synthetic lubricant composition comprising a major portion of a dialkyl ester of an aliphatic dicarboxylic acid having an alkyl portion ranging from 6 to 18 carbon atoms and an aliphatic acid portion ranging from 6 to 12 carbon atoms, from 0.05 to 0.15 weight percent of a fatty material consisting essentially of the dimer of linoleic acid, from about 1 to 20 percent by weight of a methacrylate polymer from 0 to 5 percent by weight of di(o-chlorophenyl)pheny1 phosphate, from 0 to 1 percent by weight of disalicylidene-l, 2-diaminopropane, and from 0 to 2 percent by Weight of phenothiazine.

6. A synthetic lubricant composition as described in claim 5 wherein the dialkyl ester is dioctyl scbacate.

7. A synthetic lubricant composition as described in claim 5 wherein the dialkyl ester is dioctyl azelate.

8. A synthetic lubricant composition as described in claim 5 wherein the dialkyl ester is dioctyl adipate.

9. A synthetic lubricant composition comprising a major portion of dioctyl sebacate, from about 5 to 10 percent by weight of a methacrylate polymer, about 1 to 2 percent by weight of di(o-chlorophenyl)phenyl phosphate, about 0.5 percent by weight of phenothiazine, about 0.1 percent by Weight of disalicylidene-1,2-diaminopropane, and from 0.05 to 0.15 percent by Weight of a material consisting essentially of the dimer of linoleic acid.

10. A synthetic lubricant composition comprising a major proportion of a dialkyl ester of an aliphatic dicarboxylic acid having alkyl portions ranging from 6 to 18 carbon atoms and an aliphatic acid portion containing from 6 to 12 carbon atoms, from 0.05 to 0.5 weight percent of a fatty material consisting essentially of the dimer of linoleic acid, and from about 1 to 5 Weight percent of tricresyl phosphate.

11. A synthetic lubricant composition comprising a major proportion of dioctyl sebacate, from about 5 to 10 weight percent of a methacrylate polymer, about 1 to 3 Weight percent of tricresyl phosphate, about 0.1 to 1 weight percent phenothiazine and from 0.05 to 0.15 weight percent of a material consisting essentially of the dimer of linoleic acid.

12. The method of lubricating a jet turbine aircraft engine which comprises supplying to the lubricated metal parts thereof a lubricating composition comprising a major portion of an aliphatic carboxylic acid ester of lubricating characteristics, selected from the group consisting of di- 10 esters and polyesters, and about 0.01-1 percent by weight of a fatty material consisting essentially of a compound selected from the group consisting of dimers and trimers of linoleic acid and mixtures thereof.

13. The method of lubricating a jet turbine aircraft engine which comprises supplying to the lubricated metal parts thereof a lubricating composition comprising a major portion of an aliphatic dicarboxylic acid ester of lubrieating characteristics, selected from the group consisting of diesters and polyesters, about 0.01-1 percent by weight of a fatty material consisting essentially of a compound selected from the group consisting of dimers and trimers of linoleic acid and mixtures thereof, a viscosity index improving amount of a rnethacrylate polymer, about O.11.5 percent by weight of a phenothiazine and about 13 percent by weight of a phosphate ester of the class consisting of tricresyl phosphate and di-(o-chlorophenyl)- phenyl phosphate.

References Cited in the tile of this patent UNITED STATES PATENTS 2,133,734 Moser Oct. 18, 1938 2,282,513 Downing et al May 12, 1942 2,631,979 McDermott Mar. 17, 1953 2,773,879 Sterlin Dec. 11, 1956 2,788,326 Bondi et al. Apr. 9, 1957 2,833,713 Lemmon et al May 6, 1958 2,866,755 Tierney et al Dec. 30, 1958 FOREIGN PATENTS 749,391 Great Britain May 23, 1956 OTHER REFERENCES Symposium on Synthetic Lubricants, A.S.T.M. Tech. Pub. No. 77 (1947), page 23.

Atkins et al.: Development of Additives and Lubricating Oil Compositions, Ind. and Eng. Chem, vol. 39, pages 491-497, April 1947. 

1. A SYNTHETIC LUBRICANT COMPOSITION A MAJOR PORTION OF AN ALIPHATIC CARRBOXYLIC ACID ESTER HAVING LUBRICATING PROPERTIES, SELECTED FROM THE GROUP CONSISTING OF DIESTERS OF POLYESTERS, AND A MINOR AMOUNT SUFFICIENT TO IMPROVE THE EXTREME PRESSURE PROPERTY OF THE COMPOSITION OF A FATTY MATERIAL CONSISTING ESSENTIALLY OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF DIMERS ANDTRIMERS OF LINOLEIC ACID AND MIXTURES THEREOF.
 4. A SYNTHETIC LUBRICANT COMPOSITION COMPRISING A MAJOR PORTION OFA DIALKYL ESTER OF AN ALIPHATIC DICARBOXYLIC ACID HAVING AN ALKYL PORTION RANGING FROM 6 TO 18 YLIC ACID HAVING AN ALKYL PORTION RANGING FROM 6 TO 12 CARBON ATOMS, FROM 0.01 TO 1 PERCENT BY WEIGHT OF A FATTY MATERIAL CONSISTING ESSENTIALLY OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF DIMERS AND TRIMERS OF LINOLEIC ACID AND MIXTURES THEREOF, A VISCOSITY INDEX IMPROVING AMOUNT OF A METHACRYLATE POLYER, AN OXIDATION INHIBITING AMOUNT OF PHENOTHIAZINE, AND DI(O-CHLOROPHENYL)PHENYL PHOSPHATE IN AN AMOUNT SUFFICIENT TO IMPROVE THE ANTI-WEAR PROPERTIES OF THE LUBRICANT. 